我致力于MOD10C2积雪(8天),当我夹MODIS积雪对不同区域的海拔高度对.i.e总趋势的结果。高海拔低显示积雪和低海拔显示更高的积雪。我用matlab inpolygon函数(inpolygon (yq xq,十五,青年志愿))我无法找出犯错误。首先,我以这种方式导入数据hdfvars = {‘Eight_Day_CMG_Snow_Cover’,‘Eight_Day_CMG_Clear_Index’,……“Eight_Day_CMG_Cloud_Obscured”、“Snow_Spatial_QA '};测试管理扫描= ' E: \ \ hdf测试”;dinfo = dir (fullfile(管理扫描' * .hdf '));num_files =长度(dinfo);文件名= fullfile(管理扫描,{dinfo.name});Eight_Day_CMG_Snow_Cover =细胞(num_files, 1); Eight_Day_CMG_Clear_Index = cell(num_files, 1); Eight_Day_CMG_Cloud_Obscured = cell(num_files, 1); Snow_Spatial_QA = cell(num_files, 1); for K = 1 : num_files this_file = filenames{K}; Eight_Day_CMG_Snow_Cover{K} = hdfread(this_file, hdfvars{1}); Eight_Day_CMG_Clear_Index{K} = hdfread(this_file, hdfvars{2}); Eight_Day_CMG_Cloud_Obscured{K} = hdfread(this_file, hdfvars{3}); Snow_Spatial_QA{K} = hdfread(this_file, hdfvars{4}); end Then reshaped data in this way B2 = zeros(3600,7200,24); for i = 1:3600 for j = 1:7200 B2(i,j,1:24) = reshape(Eight_Day_CMG_Snow_Cover{i,j},[1 3 2]); end end Then generate lat lon and subset the area of interest lon = -180:0.05:180; lat = -90:0.05:90; subsetqa = Eight_Day_CMG_Snow_Cover(2001:2817,4801:5741,:); then attempted to extract with elevation polygon, I tried both [monthly] and [8days] fractional snow cover data, elevation polygon are extracted from SRTM DEM. I attempted to use matlab in this way shapefile = 'shapefile.shp' ; S = shaperead(shapefile) ; N = length(S) ; for i = 1:N plot(S(i).X,S(i).Y) hold on end %% lon = load('testlon.mat') ; lon = lon.testlon ; lat = load('testlat.mat') ; lat = lat.testlat ; [X,Y] = meshgrid(lon,lat) ; data = load('testarray.mat') ; data = data.testarray ; [nx,ny,d] = size(data) ; %%Extract data iwant = cell(d,N) ; for i =1:d A = data(:,:,i) ; for j = 1:N idx = inpolygon(X(:),Y(:),S(i).X,S(i).Y) ; iwant{i,j} = A(idx) ; end Then output iwant converted into matrix in this way test = cell2mat(cellfun(@transpose,iwant,'uniform',0)); NOTE: this picture is showing polygon of only one elevation zone and we have six different elevation zones. [![enter image description here][1]][1] [1]: https://i.stack.imgur.com/UOCLB.jpg